Growth Rings

The following excerpt is from Dave Levitan’s story in Yale Environment 360 describing why U.S. cities are using green infrastructure “such as rain gardens and roadside plantings” to manage stormwater runoff. Portland is one of the cities Levitan notes for its leadership.

“‘Stormwater runoff is one of the largest water pollution issues facing the U.S. today,’ says Larry Levine, a senior attorney in the Natural Resource Defense Council’s water program.

“Now, however, numerous cities around the country — including Philadelphia, New York, Washington, Portland, and Seattle — have embarked on innovative stormwater runoff fixes that rely not so much on the old ‘gray infrastructure’ of huge, piped systems and sewage treatment plants, but rather on new green infrastructure techniques to collect and treat stormwater at the street level.

Trees intercept rainwater before it carries pollutants from pavement into rivers. (Matt Krueger)

“Green infrastructure mimics how nature handles rainwater through the use of porous surfaces, rather than impervious surfaces like roadways. These techniques are decentralized. Instead of one facility or large underground tank to store water when a big storm hits, the idea is to eliminate the need for such storage through the use of green rooftops, roadside plantings, carefully landscaped parks, rain gardens, rain barrels, and other swatches of nature dropped down inside the landscape of modern cities.

“The plants and soils collect water during a storm, preventing it from either running into sewer systems at all, or at least slowing it down to prevent overflows. Green infrastructure can also help clean some pollution from the water and can even be used to gather water for re-use.

“‘The green infrastructure approach says, ‘Let’s get the water out of those sewer systems in the first place before it has a chance to convey all that pollution into our waterways,’” says Levine. ‘And the way to do that is to put back into our built environment features that mimic the way nature handles rainwater in the natural water cycle. It doesn’t necessarily mean replacing a paved street with a park, but it means putting enough green space into the design of your roadway that you can capture runoff from that paved space.’